Phenol terminated diester compositions derived from discarboxylic acids, polyester polymers or alkyd polymers, and curable compositions containing same

ABSTRACT

The present invention is directed towards a process for preparing non-liquid crystalline phenol-terminated diester compositions characterized by the structure of formula 1: ##STR1## wherein R is an aliphatic divalent hydrocarbon radical containing 2 to 40 carbon atoms or a mixture of such radicals, provided however that R contains at least about 8 carbon atoms when n is 0 and p is 0, R 1  is an aliphatic or cycloaliphatic hydrocarbon radical containing 2 to 40 carbon atoms or a mixture of such radicals, R 2  is an aliphatic, aromatic or a mixture of aliphatic and aromatic hydrocarbon radicals having from 2 to 40 carbon atoms, A is divalent aromatic radical selected from the group consisting of phenylene, naphthylene or his phenylene, p is 0 or 1, n is 0 or an integer ranging from 1 to about 40, provided however, that p is 0 when n is 0 and p is 1 when n is an integer. 
     The invention is also directed to a single stage direct esterification or multi stage esterification processes for producing the aforementioned diesters of formula 1 either with or without the use of esterification catalysts, and is particularly directed to such processes for preparing diesters of reduced color using a low temperature process in combination with catalyst systems containing a phosphorous acid or derivative thereof.

BACKGROUND OF THE INVENTION

This application is related to copending application Ser. No. 07/404,028now abandoned, filed on Sep. 6, 1989, and is a divisional of applicationSer. No. 07/572,754, filed Aug. 24, 1990, which is not U.S. Pat. No.5,210,155.

FIELD OF THE INVENTION

The present invention relates to phenol terminated diester compositionsderived from dicarboxylic acid, polyester or alkyd backbone materials,to solid crosslinked polymer compositions prepared therefrom, and tomethods for improving coating properties of films and surface coatingsbased thereon. It also relates to methods for preparing such materialscontaining phenolic terminal end cap groups.

DESCRIPTION OF THE RELATED ART

Coating formulations usually contain a number of components. A primarycomponent is a resin which can be natural or synthetic. The resin actsas a polymeric coating binder or polymeric coating vehicle for thecoating formulation. In addition, most coatings require a solvent, andthe coating may also contain a wide variety of additives. Further, manycoatings also contain a crosslinking agent, which after application ofthe coating vehicle to a substrate, reacts chemically with the resinduring a curing stage to produce a film containing a crosslinkednetwork. The crosslinked network is necessary for the production of goodfilm properties. The curing stage can be conducted at ambient conditions("air-dry system"), or at elevated temperatures ("baked system"). Ineither case, the solvent is evaporated during the curing stage,resulting in a coating film. A number of properties are important forthe coating film, including hardness, flexibility, weather resistance(weatherability), chemical resistance, solvent resistance, corrosionresistance, adhesion to various substrates, and impact resistance. Theproperties depend on may factors including type, molecular weight,monomer composition, and glass transition temperature (Tg) of the resin;type and amount of the crosslinker; curing conditions; curing catalyst;and additives. Variations of these parameters can be used to create awide range of differences in film properties to fit requirements for anumber of diverse applications. However, it is not always possible tooptimize all of the desirable properties simultaneously.

For example, hardness and impact resistance are two desirablecharacteristics of coatings which are somewhat mutually exclusive sincehigh hardness is usually associated with films having high Tgs and lowflexibility. Conversely, high impact resistance is associated with filmshaving low Tgs and high flexibility. This necessitates a trade-offbetween high hardness and high impact resistance. It is frequentlypossible to optimize one of these properties, but at the expense of theother.

In European Patent Application No. 0 287 233 filed Mar. 28, 1988, andpublished Oct. 19, 1988, Jones et al. teach a method to simultaneouslyobtain both high hardness and high impact resistance in a coating byemploying liquid crystalline (L.C.) polymers. The L.C. polymers arecharacterized as containing mesogenic groups which impart the L.C.character to the polymer. The mesogenic groups are chemical structuresthat contain a rigid sequence of at least two, and frequently more,aromatic rings connected in the meta or para position by a covalent bondor by other rigid or semirigid chemical linkages. In addition to themesogenic groups, the polymers contain conventional polymeric unitswhich are attached to the mesogens via a covalent bond.

Jones formulates these L.C. polymers with suitable crosslinking resins,such as aminoplast resins, to create coating vehicles which, upon curingby baking yield films which have both high hardness and high impactvalues. The enhanced properties are attributed to the L.C. interactionof the various polymer chains. A mesogen which is frequently usedconsists of the internal esters of two or more molecules ofpara-hydroxybenzoic acid (PHBA). This mesogen is connected to apolymeric polyol by esterification of the OH groups of the polyol withthe residual carboxyl groups of the mesogen.

The L.C. polymers, while possessing good properties, have severaldrawbacks. First, the mesogenic groups are usually expensive tosynthesize and incorporate into the polymer. For example, multiple PHBAend groups require a large quantity of PHBA and significantly increasethe resin price. Second, the synthesis is complicated. In one method,the synthesis is based on the use of expensive and toxicdicyclohexylcarbodimide, which renders this method impractical from acommercial standpoint. Another method is based on direct esterificationof PHBA with a polyesterdiol at 230° C. in the presence ofpara-toluenesulfonic acid (p-TSA). Jones teaches that it is importantthat an acid catalyst be used and that the temperature be controlled toprovide predominantly L. C. phenolic oligoesters. Polymers produced inaccordance with the teachings of Jones result, however, in material withpoor color, an unacceptably high loss of PHBA via decarboxylation, and asizable loss of phthalic acid from the polymer due to anhydrideformation. In order to be commercially attractive, it would be verydesirable to provide the enhanced properties associated with Jones'sL.C. polymers without the above-mentioned problems.

Efforts have been made to incorporate active phenolic functionalitiesinto polymeric coating vehicles to enhance curing characteristics or theproperties of the prepared coating. However, the coatings produced inaccordance with the prior art are generally inferior or difficult toprepare.

U.S. Pat. No. 4,124,566 discloses the preparation of polyester resinsbased on the polyester reaction product of aromatic dicarboxylic acidsand diols, including bisphenols, by a two stage reaction wherein anaromatic dicarboxylic acid is first esterified by reaction with anaromatic monohydroxy compound, followed by a second stage reaction ofthis esterification product with a bisphenol compound or a mixturethereof with an aliphatic diol or dihydroxy benzene. These resins arecharacterized as having superior thermal stability, transparency andchemical stability. Because of the high content of aromatic components,the flexibility of the resins is relatively low and the glass transitiontemperature is relatively high. They are also of relatively highmolecular weight as evidenced by high reduced viscosities in excess of0.9 for the materials produced.

U.S. Pat. No. 4,028,111 discloses polyester polymers based on analternating polymer of an aliphatic dicarboxylic acid such as adipicacid and a bisphenol such as bisphenol A prepared using an excess ofbisphenol such that the bisphenol groups also end-cap the polyester. Thefree hydroxy group of the bisphenol end cap is then reacted with acompound having quinonediazide group to produce a light sensitivepolymer.

U.S. Pat. No. 4,281,101 discloses the preparation of relatively highmolecular weight polycarbonates comprising reacting a mixture of analiphatic diol, a carbonic acid bis-aryl ester such as diphenylcarbonate and a diphenyl such as bisphenol A to produce a polycarbonatepolymer containing diphenyl carbonate end groups of the diphenylcompound. These polymers may then be used as a precursor for furtherreaction with preferably aliphatic diols and phosgene to producethermoplastic aliphatic aromatic polycarbonate elastomers of highmolecular weight. Similar polycarbonates are disclosed in U.S. Pat. Nos.4,216,298 and 4,297,455.

U.S. Pat. No. 3,787,520 discloses a phenolic hydroxy terminated resinwhich may be used as a crosslinking agent in the preparation of drypowder paint systems based on crosslinkable copolymers of glycidylmethacrylate and an ethylenically unsaturated compound. The hydroxyterminated resin is prepared by reacting an epoxy compound with adiphenol such as bisphenol A to produce a polyether terminated by thediphenol.

It is also known in the art to prepare phenol terminated liquidelastomers by reacting carboxyl terminated polymers of dienes withdiphenols such as bisphenol A such that a phenolic hydroxyl group formsan end group in the polymer chain. These phenol terminated elastomersare subsequently used to cross link epoxy resins to produce animprovement in impact resistance. Examples of such systems are disclosedin U.S. Pat. Nos. 3,770,698 and 3,966,837.

U.S. Pat. No. 4,507,462 to Stille discloses biphenylene end-capped lowmolecular weight aromatic polymers and crosslinked versions thereofwhich may be prepared using a misbalanced polymerization reaction of asuitable aromatic amino ketone compound and a suitable aromaticketomethylene compound, thereafter also adding a monofunctionalbiphenylene compound such as 2-acetylbiphenlene.

Various catalysts and catalyst systems have also heretofore beendisclosed in the art for use in the preparation of mono-di- andpolyester condensation products of organic acids and hydroxy-containingaromatic monomers. For example, U.S. Pat. No. 4,610,825 discloses theuse of phosphorous acids or salts thereof as catalysts in thepreparation of monoesters of a hydroxy aromatic compound such as phenol,and a carboxylic acid containing at least four carbon atoms, such asoctanoic acid. Patentee indicates that the reaction product obtained isof high purity and low color.

SUMMARY OF THE INVENTION

The present invention is directed towards non-liquid crystallinephenol-terminated diester compositions which may be liquids or solidsand crosslinkable formulations containing a mixture of the phenolterminated diesters and an amino crosslinking agent. These diesters arecharacterized by the structure of formula 1: ##STR2## wherein R is analiphatic divalent hydrocarbon radical containing 2 to 40 carbon atomsor a mixture of such radicals, provided however that R contains at leastabout 8 carbon atoms when n is 0 and p is 0, R₁ is an aliphatic orcycloaliphatic hydrocarbon radical containing 2 to 40 carbon atoms or amixture of such radicals, R₂ is an aliphatic, aromatic or a mixture ofaliphatic and aromatic hydrocarbon radicals having from 2 to 40 carbonatoms, A is divalent aromatic radical selected from the group consistingof phenylene, naphthylene or his phenylene, p is 0 or 1, n is 0 or aninteger ranging from 1 to about 40, provided however, that p is 0 when nis 0 and p is 1 when n is an integer.

Also within the scope of the present invention are crosslinkableformulations comprising a mixture of amino crosslinking agent and phenolterminated diesters based on polyester diols containing carbonate endgroups or aliphatic and aliphatic/aromatic polycarbonates containingcarbonate end groups characterized by the structure 2: ##STR3## whereinq is an integer ranging from 1 to about 40, n is 0 or an integer rangingfrom 1 to about 40 and A, R₁ and R₂ are as defined above.

These diester oligomers or polymers are characterized by a numberaverage molecular weight within the range of from about 500 to about10,000.

The invention is also directed to a single stage direct esterificationor multi stage esterification processes for producing the aforementioneddiesters of formula 1 either with or without the use of esterificationcatalysts, and is particularly directed to such processes for preparingdiesters of reduced color using a low temperature process in combinationwith catalyst systems containing a phosphorous acid or derivativethereof.

The phenol terminated diester compositions of this invention may be usedas a resinous component in curable coating and paint formulations, alsocontaining an amino crosslinking agent and other optional ingredientssuch as crosslinking catalyst, fillers, pigments and the like. Coatingsprepared in accordance with this invention exhibit both high hardnessand high impact strength, excellent weatherability, good corrosionresistance and hydrolytic stability, good solvent resistance andadhesion as well as low color and low impurity levels. These propertiesare produced without the incorporation of L.C. polymers or mesogenicgroups into the composition, thus avoiding the many drawbacks of L.C.based polymers or polymer compositions.

DETAILED DESCRIPTION OF THE INVENTION

A first embodiment of this invention is directed towards diesters of thestructure of formula 1 above and their method of preparation. Thesediesters may be generally categorized as the esterification product of abackbone material containing terminal carboxyl groups and a dihydricphenol such that each terminal group present on the backbone materialreacts with a single hydroxy group present on the dihydric phenolresulting in an oligomer or polymer containing a free aromatic hydroxygroup at terminal ends of the polymer chain. The backbone material maybe composed of: (a) an aliphatic dicarboxylic acid or mixtures of suchacids, having from about 8 to about 40 carbon atoms in which case n andp of formula 1 would each be o; and (b) a carboxy-terminated polyesteror polyester/alkyd reaction product of one or more aliphaticdicarboxylic acids having from 2 to 40 carbon atoms, or mixtures of suchacids with one or more aromatic dicarboxylic acids having from 8 to 40carbon atoms, in which case in formula 1, n would be an integer rangingfrom 1 to about 40 and p would be 1.

A second embodiment of this invention is directed towards crosslinkablecoating formulations comprising a mixture of amino crosslinking agentand one or a mixture of diesters of the type (a) or (b) described above.

Yet another embodiment of the invention is directed towardscrosslinkable coating formulations comprising a mixture of an aminocrosslinking agent and one or a mixture of two or more diesters based onthe esterification product of the aforementioned dihydric phenol and abackbone material having carbonate end groups composed of: (c) a diol ordiol lengthened via carbonate linkages (--OCOO groups) and containingterminal carbonate groups linking the diol or lengthened diol backboneto the terminal phenol end groups such as shown in formula 2 above, inwhich case n would be 0 and q would be equal to or greater than 1; (d) apolyester diol lengthened via carbonate linkages and containing terminalcarbonate groups linking the lengthened polyester diol backbone to theterminal phenol end groups such as shown in formula 2 above in whichcase n would be equal to or greater than 1 and q would be greater than1; and (e) a polyester diol containing terminal carbonate groups linkingthe polyester diol backbone to the terminal phenol end groups such asshown in formula 2 above in which case n would be greater than i and qwould be equal to 1.

Diesters of type (a) described above are characterized by the followinggeneral formula 3: ##STR4## wherein R' is an aliphatic radicalcontaining from about 8 to about 40 carbon atoms and A is as definedabove.

Diesters of the type (b) described above are characterized by thefollowing general formula 4: ##STR5## wherein R is an aliphatic orcycloaliphatic radical containing from 2 to about 40 carbon atoms, n isan integer ranging from 1 to about 40, and R₁, R₂ and A are as definedabove.

Diesters of type (c) above are characterized by formula 2 where n equals0 and q is equal to or greater than 1. These materials are prepared byforming the condensation product of an aliphatic or cycloaliphatic diolhaving 2 to 40 carbon atoms with a diphenol such as bisphenol A and adiphenyl carbonate to form a polycarbonate having diphenyl carbonate endgroups, followed by a subsequent polycondensation reaction of thisprecursor with a diphenol, such as bisphenol A, and phosgene to form thephenol terminated diesters. These materials are disclosed in U.S. Pat.No. 4,281,101, the disclosure of which patent is incorporated herein byreference.

Diesters of type (d) above are characterized by formula 2 where n isequal to or greater than 1 and q is greater than 1. These materials areprepared by forming the condensation product of a polyester diol and acarbonic acid bis-aryl ester such as diphenyl carbonate to form apolyester diol which has been chain lengthened via carbonate linkinggroups, followed by further polycondensation with a diphenol such asbisphenol A to form the phenol terminated diesters. These materials aredisclosed in U.S. Pat. No. 4,297,455, the disclosure of which isincorporated herein by reference.

Diesters of the type (e) above are characterized by formula 2 where n isgreater than I and q is equal to 1. These materials are prepared byforming the condensation product of a polyester diol with a carbonicacid bis-aryl ester such as diphenyl carbonate to form thepolyester-diol his-carbonic acid ester, followed by polycondensation ofthis precursor with a diphenol such as bisphenol A to form the phenolterminated diesters. These materials are disclosed in U.S. Pat. No.4,216,298, the disclosure of which is incorporated herein by reference.

The phenol terminated diester polymer compositions of this inventioncontain no liquid-crystalline polymers or mesogenic groups, and may befurther characterized as having glass transition temperatures (Tg) aslow as -40° C. for the lower viscosity polymers and up to +100° C. ormore for the viscous or solid polymers. These polymers may be convertedinto a formulated coating by adding an amino crosslinking agent and theusual solvents, pigments, and additives such as flow modifiers andstabilizers which are employed in coating compositions. The formulatedcoating may be applied to a substrate in the usual manner, e.g., bybrushing, spraying, roller coating, or dipping. The coated substrate isthen baked to form the final film by simultaneously evaporating off thesolvent followed by crosslinking. The films of the invention arecharacterized by improved properties such as simultaneous high hardnessand high impact resistance, excellent weatherability, good corrosionresistance and hydrolytic stability, good solvent resistance, lowimpurity levels, and good adhesion when compared with films made withsimilar (molecular weight, functionality, etc. ) polymeric materialscontaining no phenol terminal groups.

The diphenols which may be connected by an ester linkage to the terminalcarboxyl or carbonate groups present in the backbone material arearomatic compounds having hydroxy substituent groups attached directlyto the aromatic ring and may be represented by the structure:

    HO--A--OH

wherein A is a divalent radical selected from the group consisting ofphenylene, naphthylene or his phenylene radicals having the structure:##STR6## wherein m is 0 or 1, X is selected from the group consisting ofa C₁ to C₁₂ hydrocarbon divalent radical, cycloaliphatic divalentradical having 5-12 carbon atoms, S, O, and R₄ --C--R₄ wherein R₄ may bethe same or different and is selected from the group consisting ofhydrogen, C₁ to C₆ alkyl, cycloalkyl, phenyl and CF₃, and Y and Z areindependently selected from the group consisting of hydrogen, halogen,C₁ to C₄ alkyl and C₁ to C₄ alkoxy.

Examples of preferred polyhydric phenols include hydroquinone,resorcinol phenolphthalein, 1,4-dihydroxynaphthalene,1,5-dihydroxynaphthalene, and 2,6-dihydroxynaphthalene. Examples ofpreferred diphenols include 2,2-bis(4-hydroxyphenyl) propane [bisphenolA], 1,1-bis(4-hydroxyphenyl) cyclohexane [bisphenol Z],1,1-bis(4-hydroxyphenyl) ethane, bis (4-hydroxyphenyl)methane, 1,2-bis(4-hydroxyphenyl) ethane, bis (4-hydroxyphenyl) cyclohexylmethane,3,3-bis (4-hydroxyphenyl) pentane, bis(4-hydroxyphenyl) ether, bis(4-hydroxyphenyl) sulfide, and 2,2-bis (4-hydroxyphenyl)hexafluoropropane.

The preferred diphenol capping agent for the purposes of this inventionis bisphenol A.

The diphenols are connected to the carboxy or carbonate terminatedbackbone materials such that a single hydroxy group present in thediphenol reacts with a terminal aliphatic carboxyl or carbonyl grouppresent on each end of the backbone material so that the material iscapped on both ends via an ester linkage as depicted by formulas 1, 2, 3and 4 above.

The R, R₁ and R₂ radicals may be linear or branched aliphatic orcycloaliphatic and R₂ may also be phenylene, naphthylene and hisphenylene type aromatic radicals. These radicals may also containinternal ester groups. In the more preferred embodiment of theinvention, the R, R₁ and R₂ radicals are essentially linear or branchedalkenyl or alkylidene.

In the most preferred embodiment of the invention, the phenol terminateddiester component of the compositions of this invention is based on acarboxy terminated polyester polymer and has the structure of formula 5:##STR7## wherein R is a bivalent aliphatic hydrocarbon radical havingfrom 2 to 12 carbon atoms, R₁ is a bivalent aliphatic hydrocarbonradical having from 2 to 12 carbon atoms, R₂ is the same as R or abivalent aromatic radical having from 6 to 40 carbon atoms, includingaromatic carbon atoms, m is 1, n is 1 to 40, and X is as set forthabove. The more preferred range for n in this embodiment is from about 2to about 20 and X is preferably C(CH₃)₂.

In the other most preferred embodiment of this invention, the phenolterminated diester component is based on a carboxy terminateddicarboxylic acid and has the structure of formula 6: ##STR8## whereinR' is an aliphatic hydrocarbon radical or mixtures thereof having from 8to 40 carbon atoms and x and m are as set forth in formula 5 above. Inthe most preferred embodiment, R' contains from 12 to 38 carbon atoms.

The minimum number average molecular weight for compounds of formulas 5and 6 above which include the polymer end-capping dihydric phenols intheir structure is at least about 500, more preferably at least about1000.

The carboxy terminated polyester polymer backbone material such asdepicted in formula 5 above may be formed by the condensation reactionof a diol with a molar excess of a dicarboxylic acid. The diol generallycontains 2 to 20 carbon atoms and preferably contains about 2 to 10carbon atoms, and may also contain internal ester groups. Some preferredexamples of the diols are one or more of the following: neopentylglycol; ethylene glycol; hexamethylenediol; 1,2-cyclohexanedimethanol;1,3-cyclohexanedimethanol; 1,4-cyclohexanedimethanol; diethylene glycol;triethylene glycol; tetraethylene glycol; dipropylene glycol;polypropylene glycol; hexylene glycol; 2-methyl-2-ethyl-l,3-propanediol;2-ethyl-l,3-hexandediol; 1,5-pentanediol; thiodiglycol; 1,3-propanediol;1,2-propanediol; 1,2-butanediol; 1,3-butanediol; 2,3-butanediol;1,4-butanediol; 2,2,4-trimethyl-l,3-pentanediol; 1,2-cyclohexanediol;1,3-cyclohexanediol; 1,4-cyclohexanediol; neopentyl diol hydroxy methylisobutyrate, and mixtures thereof.

The carboxy terminated dicarboxylic acids which may be used either inconjunction with the above referenced diols to produce the carboxylterminated polyester polymer backbone used in preparing capped polymersof formula 5 above, or alone in producing the capped dicarboxylic acidmaterials of formula 6 above are dicarboxylic acids which contain from 2to about 40 aliphatic carbon atoms or about 6 to about 40 carbon atoms,including aromatic atoms, and at least 2 carboxyl groups which-mayalternatively be present in the form of anhydride groups or equivalentester forming derivatives such as the acid halide or methylester. Thedicarboxylic acids are preferably one or more of the following: phthalicanhydride, terephthalic acid, isophthalic acid, adipic acid, succinicacid, glutaric acid, fumaric acid, maleic acid, cyclohexane dicarboxylicacid, azeleic acid, sebacic acid, dimer acid, pyromellitic dianhydride,substituted maleic and fumaric acids such as citraconic, chloromaleic,mesaconic, and substituted succinic acids such as aconitic and itaconic,and mixtures thereof. The most preferred acids for the purposes of thisinvention are linear saturated or unsaturated aliphatic dicarboxylicacids having from 2 to 10 carbon atoms such as succinic, glutaric,adipic, and similar materials. As indicated above, thecarboxy-terminated dicarboxylic acids preferably contain at least about8 carbon atoms when these materials are used alone in producing theend-capped dicarboxylic acid materials of formula 6 above.

In another embodiment, carboxy terminated oligomeric backbone materialused to synthesize the diester polymers is a short chain alkyd resin. Analkyd resin is an oil modified polyester resin and broadly is theproduct of the reaction of a dihydric alcohol and a dicarboxylic acid oracid derivative and an oil, fat or carboxylic acid derived from such oilor fat which acts as a modifier. Such modifiers are typically dryingoils. The dihydric or polyhydric alcohol employed is suitably analiphatic alcohol. Suitable alcohols include glycol, 1,2- or1,3-propylene glycol, butanediol, hexanediol, neopentyl glycol, and thelike. Mixtures of the alcohols may also be employed. The dicarboxylicacid, or corresponding anhydrides, may be selected from a variety ofaliphatic carboxylic acids or mixtures of aliphatic and aromaticdicarboxylic acids. Suitable acids and acid anhydrides include, by wayof example, succinic acid, adipic acid, phthalic anhydride, isophthalicacid, and bis 3,3' 4,4'-benzophenone tetracarboxylic anhydride. Mixturesof these acids and anhydrides may be employed to produce a balance ofproperties. As the drying oil or fatty acid there is suitably employed asaturated or unsaturated fatty acid of 12 to 22 carbon atoms or acorresponding triglyceride, that is, a corresponding fat or oil, such asthose contained in animal or vegetable fats or oils. Suitable fats andoils include tall oil, castor oil, coconut oil, lard, linseed oil, palmoil, peanut oil, rapeseed oil, soybean oil and beef tallow. Such fatsand oils comprise mixed triglycerides of such fatty acids as caprylic,capric, laurie, myristic, palmitic, and stearic and such unsaturatedfatty acids as oleic, eracic, ricinoleic, linoleic and linolenic.Chemically, these fats and oils are usually mixtures of two or moremembers of the class.

These carboxyl terminated alkyd backbone polymers generally should havea number average molecular weight of from 1,000 to 3,000.

The corresponding carbonate terminated alkyds may also be used asbackbone materials by forming the hydroxy terminated alkyd backbone in amanner analogous to the formation of the hydroxy terminated polyesterbackbone described above and using the reactants as set forth above.

As indicated above, the diesters of this invention are preferablyprepared using saturated or unsaturated aliphatic diol and dicarboxylicacid starting materials. It may, however, be desirable to use somequantity of tri or tetra functional aliphatic reactants to influenceviscosity and other properties of the diester material. This may beaccomplished by including minor quantities, e.g. less than about 2 molepercent, of polyfunctional polyols and/or polycarboxylic acids in theesterification recipe. Examples of suitable polyols includetrimethylolethane, triemthylol propane, glycerol and pentaerythritol.Examples of suitable polycarboxylic acids include trimellitic acid oranhydride.

As indicated above, the phenol terminated diesters of the presentinvention are particularly useful as resinous components incrosslinkable paint and coating compositions also containing an aminocrosslinking agent, and other conventional additives normally present insuch compositions.

The amino crosslinking agents used in the present invention are wellknown commercial products. They are organic compounds of the generalstructural type, as shown below: ##STR9## wherein: ##STR10##

The amino crosslinking resins are produced by companies such as AmericanCyanamid, and Monsanto, and are made by the reaction ofdi(poly)amide(amine) compounds with formaldehyde and, optionally, loweralcohol.

The amino crosslinking resins that are currently produced commerciallyare based on: ##STR11##

Examples of suitable amino-crosslinking resins for the diesters include:

Melamine based ##STR12## wherein R is the following: R=CH₃ (Cymel® 300,301, 303);

R=CH₃, C₂ H₅ (Cymel® 1116);

R=CH₃, C₄ H₉ (Cymel® 1130, 1133);

R=C₄ H₉ (Cymel® 1156); or

R=CH₃, H (Cymel® 370, 373, 380, 385).

The preferred melamine is hexamethoxymethylmelamine.

Benzoquanamine based resin ##STR13## wherein R=CH₃, C₂ H₅ (Cymel® 1123).

Urea based resins ##STR14## wherein R=CH₃, H (Beetle 60, Beetle 65); or

R=C₄ H₉ (Beetle 80).

Gycoluryl based resins ##STR15## wherein: R=CH₃, C₂ H₅ (Cymel® 1171); or

R=C₄ H₉ (Cymel® 1170).

In the present invention, the ratio of the active crosslinking groups,e.e., methylol (alkoxymethyl) groups of the amino crosslinking agent tothe phenol groups on the phenol terminated diester is desirably fromabout 1.0: 1.0 to 15.0: 1.0, more preferably from about 1.0: 1.0 to 5.0:1.0, most preferably from about 1.5: 1.0 to 4.0: 1.0.

On a weight basis, the amount of amino crosslinking agent effective forcuring the crosslinkable binder generally ranges from about 3 to about50 percent by weight, more preferably from about 15 to about 40 percentby weight based on the combined weight of the amino crosslinking agent,polymer and any other crosslinkable polymer constituent of thecomposition.

In general, quantities of crosslinking agent required to cure thecomposition are inversely proportional to the number average molecularweight of the ester phenol-capped polymer composition. Quantities ofcrosslinking agent on the higher side of this range are required toproperly cure ester phenol-capped polymer compositions having arelatively low number average molecular weight, e.g., from about 500 toabout 3,000, whereas lesser amounts of the crosslinking agent arerequired to properly cure ester phenol-capped polymers having a highernumber average molecular weight, e.g., from about 3,000 up to about10,000.

The esterification of the carboxy terminated dicarboxylic acid backboneor the preparation of the diphenol terminated polyester or alkyd ispreferably carried out by one of several methods. In a first embodiment,a two stage reaction is used wherein a carboxy terminated polyester isformed by mixing a molar excess of aliphatic dicarboxylic acid with theappropriate diol, such as neopentyl glycol. Preferably, the molar ratioof dicarboxylic acid to diol is at least n+1:n, wherein n represents thenumber of moles of diol. The use of such a molar excess of acid insuresthat the major proportion of the resulting oligomer molecules will beterminated by acid groups. A suitable solvent and catalyst mayoptionally be added and the solution is stirred and heated from about140° to 220° C. After most of the water of reaction has been removed,the diphenol is added and the second stage of the reaction is alsocarried out at temperatures between about 150°-260° C. The reaction canbe completed by increasing the reaction temperature, preferably up toabout 260° C. to esterify residual reactants.

In another embodiment, the esterification and capping reactions may becarried out in a single stage reaction. Thus, all the raw materials forforming the phenol terminated diester, including optional catalyst, maybe combined and heated to a temperature of from about 140° to 220° C.Where the reactants include an aliphatic dibasic acid and aliphaticdiol, these reactants will condense first because of the very highreactivity of aliphatic diols with aliphatic dibasic acids to form acarboxy terminated polyester. Then, the carboxyl functional end groupsof the polyester will condense with a hydroxyl group present on thediphenol to produce the end-capped diester, during which the reactiontemperatures may range from about 150°-260° C. as in the embodiment setforth above.

In another embodiment, a two stage reaction is used. In the first stage,the diphenol is mixed with a molar excess of a dicarboxylic acid such asadipic acid. Preferably, the ratio of dicarboxylic acid to the diphenolranges from about 1:1 to 10:1. A suitable solvent and catalyst mayoptionally be added and the solution is stirred and heated from140°-200° C. The excess amount of acid which will be subsequentlyreacted helps to drive the reaction rate which allows a lower reactiontemperature to be used. After most of the water of reaction has beenremoved, the aliphatic diol or mixture of aliphatic diols are added andthe second stage of the reaction is also carried out at temperaturesbetween 140°-200° C. This technique keeps the temperature below 200° C.The reaction can be completed by increasing the reaction temperature,preferably between about 200° and 230° C., to esterify residualreactants.

In another embodiment, the diesters based solely on an aliphaticdicarboxylic acid backbone are prepared by esterifying an aliphaticdicarboxylic acid with the diphenol at a reaction temperature belowabout 250° C.

The molar ratio of dihydric phenol to dicarboxylic acid and todicarboxylic acid plus diol where carboxy terminated polyester backbonepolymers are formed, generally should be at least 2: (n+l): nrespectively wherein n represents the number of moles (if any) of diol.Thus, for example, 2 moles of dihydric phenol may be reacted with onemole of dicarboxylic acid in the case where end capped acid esters areformed, and 2 moles of dihydric phenol may be reacted with 2 moles ofdicarboxylic acid and one mole of diol in the case where end-cappedesters of carboxy terminated polyesters are formed.

As indicated above, the diesters of this invention are free of mesogenicgroups. To insure that such mesogenic groups are not formed particularlywhen an aromatic dicarboxylic acid is utilized as an ester-formingreactant, i.e., when R₂ in formula 1 above is an aromatic radical, avariation in above synthesis procedure may be employed. In oneembodiment of this process variation, a three step procedure is usedwherein a polyester diol is produced in the first step by forming thepolyester condensation product of a molar excess of diol, such asneopentyl glycol, with a dibasic acid, which may be aliphatic, aromaticor mixtures of aliphatic and aromatic dicarboxylic acids, at a reactiontemperature below about 200° C. In the second step, the resultingpolyester diol is esterified with an aliphatic dicarboxylic acid, suchas adipic acid, to produce a dicarboxy functional polyester. The finalstep is an esterification of the dicarboxy functional polymer with adiphenol, such as bisphenol-A, at a reaction temperature below about250° C.

In a variation of the above variation, the diphenol may be first reactedwith an excess of the aliphatic dicarboxylic acid at a temperature belowabout 200° C to form the aliphatic half ester. This material may then bereacted with a mixture of aliphatic diol and dicarboxylic acid(aromatic, aliphatic or mixtures of aromatic and aliphatic) at atemperature below about 200° C. to form the phenol terminated diesterfree of mesogenic groups.

Diesters containing terminal carbonate groups linking the backbonematerial to the phenol may be prepared using procedures analogous to theabove by condensing an aliphatic diol, a hydroxy terminated polyester oralkyd diol with diphenyl carbonate, followed by reaction with thediphenol, or by first forming the half ester of the diphenol anddiphenyl carbonate followed by reaction with an aliphatic diol, hydroxyterminated polyester or hydroxy terminated alkyd. Processes forpreparing these materials are disclosed in U.S. Pat. Nos. 4,281,101,4,297,455, and 4,216,298.

It is generally known that the direct esterification of phenols bycarboxylic acids does not proceed as readily as the esterification ofaliphatic hydroxyl groups with carboxylic acids. In most cases whenesterification of phenols is required, anhydrides or acid chlorides areused--e.g., the Schotten Baumann technique, rather than directesterification. However, the use of anhydrides or acid chlorides forcommercial production of phenyl esters is not practical because of thecost of the reagents, the highly corrosive nature of the hydrogenchloride which is formed when acid chlorides are used, as well as thesubstantial quantity of by-products which must be utilized or disposedof in both cases. Therefore, in order to provide a commerciallyacceptable process for the production of phenol terminated polymers,direct esterification of phenolic hydroxyl groups with carboxyl groupsoffers distinct advantages.

One method for the direct esterification of phenols was discovered byLowrance and is disclosed in U.S. Pat. No. 3,772,389. This method uses aH2SO₄ /H₃ BO₃ catalyst and proceeds with the high efficiency at130°-150° C. However, the phenol terminated diester which is producedwhen this catalyst is used has intense color which limits application ofthe process.

It was surprisingly discovered that, at higher temperatures (190°-260°C.), aliphatic carboxylic groups can esterify phenols at a reasonablerate even without a catalyst. It was also found that certaincombinations of compounds are particularly effective catalysts fordirect esterification. They include preferably two and three valentmetal compounds such as oxides, hydroxides, weak acid salts and thelike, and their combinations with a strong acid such as sulfonic acid,halogen acids and the like. For metal compounds having the structureM(OH)_(n), the ratio of equivalents of acid to equivalents of M(OH)_(n)is <n, preferably <0.5 n. A wide range of Group I to Group VI metals canbe used in the reaction which include Be, A1, Cr, Mn, Fe, Co, Ni, Cu,Zn, Ga, Sn, Pb, Bi, and the like. Examples of preferred metal compoundsused in the reaction are zinc acetate, calcium oxide, and sodiumbicarbonate. Examples of metal compounds used in combination with strongacids are magnesium acetate methane-sulfonic acid, aluminum hydroxyacetate-methane sulfonic acid and zinc acetate-methane sulfonic acid.These catalytic systems are effective within an esterificationtemperature range of about 140°-200° C., preferably about 150°-190° C.

Another group of compounds effective as phenol esterification catalystsfor the purposes of this invention are combinations of phosphorus basedacids, such as, phosphorous or phosphoric acid with co-catalysts such asboron oxide, boric acid, and the metal (II, III) salts as defined above.Examples of such catalyst systems include H₃ PO₃ --H₃ BO₃ and H₃ PO₃--ZnAc₂. These systems catalyze phenol esterification in the temperaturerange of 150°-200° C.

The synthesis of phenol terminated diesters using the above mentionedsystems results in products with better color than the those obtainedusing the H₂ SO₄ /H₃ BO₃ catalyst described in U.S. Pat. No. 3,772,389.

In general, the use of high reaction temperatures for both the catalyzedand uncatalyzed reactions tends to promote color body formation. Thisobservation can also be made with respect to the H₂ SO₄ /H₃ BO₃ catalystsystem described above. Catalysts which can act as oxidants orco-oxidants, such as H₂ SO₄, are a possible cause of colorbody-formation. Thus, the present invention additionally provides forthe use of catalyst systems based on reducing acids which are known tohave reducing rather than oxidizing properties. Reducing acids are acidsin which the central atom is at an intermediate oxidation state.Examples of such acids are phosphorous acid, hypophosphorous acid aswell as their phosphite salts and sulfinic acids such as toluenesulfinic acid, and mixtures thereof. These acids are effective ascatalysts for the esterification of phenols with carboxylic acid attemperatures in the range of about 130°-190° C., preferably 140°-180° C.The synthesis of esters and particularly phenol terminated diester usingthese acids as catalysts results in products which have very low color.For example, a phenol terminated polymer having Gardner color <1 may beobtained when hypophosphorous acid is used as a catalyst.

Where a condensation catalyst is included in the reaction mixture, it isgenerally used in quantities ranging from about 0.01 wt. % up to about2.0 wt. % based on the weight of reactants.

The esterification reaction is preferably carried out in a solventmedium which is capable of dissolving at least one of the reactants. Thesolvent should be inert during the esterification reaction. Preferredsolvents are hydrocarbons. Aromatic hydrocarbon solvents are mostpreferred.

The purity of phenol capped diester described above and as representedby the structure of formulas 1 and 2 above is generally not 100%. Inpractice the bulk of the product is as represented in formulas 1 and 2above but also contains significant amounts of unreacted dihydric phenolas well as a diester of the dihydric phenol wherein the dihydric phenolis present as at least one recurring monomer unit in the polyesterbackbone chain. Generally the reaction product comprises from about 40to 65 weight percent of phenol capped product as shown in the formulasabove, the balance being a mixture of unreacted dihydric phenol anddihydric phenol diester.

The present invention also provides for a novel coating compositionformed by combining the phenol terminated diesters of this invention, anamino crosslinking agent, and optionally a solvent. Application of theformulated coating can be made via conventional methods such asspraying, roller coating, dip coating, etc., and then the coated systemmay be cured by baking.

The same or different solvent(s) which are optionally used during thesynthesis of the diester to dissolve reactants may also be added duringthe formulation of the coating composition to adjust viscosity so as toprovide a formulation with a viscosity usually between about 10centipoise to 10 poise. One or more solvents can be used. In many cases,a single solvent is used to solubilize the system. However, in othercases it is often desirable to use mixtures of solvents in order toeffect the best solubilization, and in particular a combination ofaromatic solvents with oxygenated solvents is preferred. Suitablearomatic solvents include toluene, xylene, ethylbenzene, tetralin,naphthalene, and solvents which are narrow cut aromatic solventscomprising C₈ to C₁₃ aromatics such as those marketed by Exxon CompanyU.S. A. under the name Aromatic 100, Aromatic 150, and Aromatic 200. Theoxygenated solvents should not be extremely polar such as to becomeincompatible with the aromatic solvents. Suitable oxygenated solventsinclude propylene glycol monomethyl ether acetate, propylene glycolpropyl ether acetate, ethyl ethoxypropionate, dipropylene glycolmonomethyl ether acetate, propylene glycol monomethyl ether, propyleneglycol monopropyl ether, dipropylene glycol monomethyl ether, diethyleneglycol monobutyl ether acetate, ethylene glycol monoethyl ether acetate,ethylene glycol monobutyl ether acetate, ethylene glycol monoethylether, ethylene glycol monobutyl ether, diethylene glycol monoethylether, diethylene glycol monoethyl ether acetate, Dibasic ester (amixture of esters of dibasic acids marketed by DuPont), ethyl acetate,n-propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate,amyl acetate, isoamyl acetate, mixtures of hexyl acetates such as thosesold by Exxon Chemical Company under the brand name EXXATE® 600,mixtures of heptyl acetates such as those sold by Exxon Chemical Companyunder the brand name EXXATE® 700, acetone, methyl ethyl ketone, methylisobutyl ketone, methyl amyl ketone, methyl isoamyl ketone, methylheptyl ketone, isophorone, isopropanol, n-butanol, sec.-butanol,isobutanol, amyl alcohol, isoamyl alcohol, hexanols, and heptanols. Thelist should not be considered as limiting, but rather as examples ofsolvents which are useful in the present invention. The type andconcentration of solvents are generally selected to obtain formulationviscosities and evaporation rates suitable for the application arebaking of the coatings. Typical solvent concentrations in theformulations range from 0 to about 75% by weight with a preferred rangebetween about 5 and 50% by weight and a most preferred range betweenabout 10 and 40% by weight. For the preparation of high solids coatings,the amount of solvent used in the coating formulation is preferably lessthan 40% of the weight of the formulation.

Satisfactory baking schedules for formulations of the present inventionvary widely including, but not limited to, low temperature bakes ofabout 20 to 30 minutes at temperatures between 200 and 220° F for largeequipment applications and high temperature bakes of about 5 to 10seconds in 600 to 700° F air for coil coating applications. In general,the substrate and coating should be baked at a sufficiently hightemperature for a sufficiently long time so that essentially allsolvents are evaporated from the film and chemical reactions between thepolymer and the crosslinking agent proceed to the desired degree ofcompletion. The desired degree of completion also varies widely anddepends on the particular combination of cured film properties requiredfor a given application.

Required baking schedules also depend on the type and concentration ofcatalysts added to the formulations and on the thickness of the appliedcoating film. In general, thinner films and coatings with higherconcentrations of catalyst cure more easily, i.e., at lower temperaturesand/or shorter baking times.

Acid catalysts may be used to cure systems containing hexamethoxymethylmelamine and other amino crosslinking agents, and a variety of suitableacid catalysts are known to one skilled in the art for this purpose.These include, for example, p-toluene sulfonic acid, methane sulfonicacid, nonylbenzene sulfonic acid, dinonylnapthalene disulfonic acid,dodecylbenzene sulfonic acid, phosphoric acid, phosphorous acid, phenylacid phosphate, butyl phosphate, butyl maleate, and the like or acompatible mixture of them. These acid catalysts may be used in theirneat, unblocked form or combined with suitable blocking agents such asamines. Typical examples of unblocked catalysts are the King Industries,Inc. products with the tradename K-CURE®. Examples of blocked catalystsare the King Industries, Inc. products with the tradename NACURE®.

The amount of catalyst employed typically varies inversely with theseverity of the baking schedule. In particular, smaller concentrationsof catalyst are usually required for higher baking temperatures orlonger baking times. Typical catalyst concentrations for moderate bakingconditions (15 to 30 minutes at 275° F.) would be about 0.3 to 0.5 wt.%catalyst solids per diester plus crosslinking agent solids. Higherconcentrations of catalyst up to about 2 wt.% may be employed for curesat lower temperature or shorter times. Formulations containingsufficient residual esterification catalyst, such as phosphorous acid,may not require the inclusion of any additional crosslinking catalyst toeffect a proper cure at lower curing temperatures.

In the case of formulations of this invention containinghexamethoxymethyl melamine as the crosslinking agent and p-toluenesulfonic acid as the catalyst, preferred curing conditions at dry filmthickness of about 1 mil are catalyst concentration between about 0.05and 0.6 wt.%, based on polymer solids plus crosslinking agent solids,baking temperature between 200° and 400° F. and baking time betweenabout 5 and 60 minutes. Most preferred curing conditions are catalystconcentration between about 0.05 and 0.3 wt.%, baking temperaturebetween about 250° and 350° F. and baking time between about 20 and 40minutes.

As described above, the formulations of this invention are characterizedby improved weather resistance. However, additional improvements in thisand other properties can be achieved by including stabilizers andstabilizing systems into the formulation. Among compounds providingimprovements in weather resistance are HALS (hindered amine lightstabilizers), UV-screeners, antioxidants, etc. To achieve the desiredcolor, the composition can be formulated with one or a mixture ofvarious pigments. If pigment is added to the coating formulation, thenthe ratio of pigment to diester and amino crosslinking agent desirablyranges from about 0.5:1.0 to 5.0:1.0, preferably from about 0.8:1.0: to2.0:1.0.

Another formulating tool to improve weather resistance are siliconeresins used to replace part of the diester component of the compositionand impart better weather resistance to the whole system. All of theseformulating approaches can be used with the diester compositions of thepresent invention.

The diester composition of this invention may also be blended with othercrosslinkable polymer materials to improve the physical and chemicalproperties of the latter. Examples of suitable blend polymers includeacrylic and methacrylic polymers and copolymers, epoxy resins, alkydresins, epoxy/phenolic resins, epoxy/acrylic resins, aromatic andaliphatic urethane polymers, chlorinated rubber, nitrocellulose andother polyester resins. Respective blend ratios of 1:20 to 20:1 may beused. The diesters of this invention are particularly effective inimproving the chemical resistance of alkyd resins when blended therewithat levels of from about 5 to 25% by weight.

The following examples illustrate but are not intended to limit thescope of this invention.

EXAMPLES

The following example shows the preparation of a composition containingbisphenol terminated polyester using a mixed catalyst system (H₃ BO₃ /H₃PO₃ ) under relatively mild esterification conditions (160°-190° C.).

EXAMPLE 1

Into a 2 liter four-necked flask equipped with a mechanical stirrer,heating mantle, nitrogen sparget, 10 inch column packed with glass beadson top of which is a Dean Stark trap and chilled water condenser, andthermometer fitted with temperature controller, are charged 228.3g.bisphenol A (BPA), 146g. adipic acid (AA), 52g. neopentyl glycol (NPG),100g. Aromatic 100 solvent (a narrow-cut solvent of C₈ -C₁₀ aromaticsmarketed by Exxon Company USA), 50g. Xylene, 1.5 g. Boric acid (H₃ BO₃),and 2.0 g. Phosphorous Acid (H₃ PO₃). The contents are heated tomelting, stirred, and heating is continued to about 160° C. where thesolvent/water azeotrope starts to distill out. The solvent phase iscontinuously removed from-the Dean Stark trap and returned to the flask.Water removal is used to monitor the reaction. The temperature is raisedperiodically to keep water removal at an appreciable rate. Heating iscontinued and the temperature allowed to rise as the water is removed toa final temperature of 190 ° C. The reaction is stopped after 93% of thetheoretical amount of water has been removed, which takes 13.5 hours.The product is cooled and discharged. The product has an NVM(nonvolatile matter) content of 86.5%, strong acid number 1.0,carboxylic acid number 15.3, and a reduced viscosity of 0-.08 for a 10%solution in glacial acetic acid. The composition of this phenolterminated polyester can be abbreviated as follows: BPA/AA/NPG: 2/2/1.

EXAMPLES 2-5

The procedure in Example 1 is used to produce other bisphenol terminatedpolymers. Variations in monomer ratio, catalyst type and amount, amountof solvent, and polymerization conditions are used as shown in Table 1.Water removal is used to monitor the reaction rate and to determine thereaction time. The results are tabulated in Table 1.

EXAMPLES 6-17

The procedure of Example 1 is repeated but with other catalyst systems,solvents, and polymerization conditions, as shown in Table 2.

The following example relates to the preparation of clear films from thebisphenol terminated polyesters.

EXAMPLE 18

A clear formulation is prepared by adding the following ingredients intoa clean glass jar (or metal can):

    ______________________________________                                        18.2 g of bisphenol terminated polyester resin of                                    Example 1 (86.5% nonvolatile content)                                  5.2 g  hexamethoxymethyl melamine (HMMM) as CYMEL                                    303                                                                    3.3 g  methyl amyl ketone                                                     3.3 g  methyl ethyl ketone                                                    30.0 g total                                                                  ______________________________________                                    

                                      TABLE 1                                     __________________________________________________________________________                                Reactions Conditions                                 Monomer                            Water                                      Mole Ratio,                                                                           Catalyst         Time                                                                              Temp  Off-Take,                                                                              Reduced                        EX.                                                                              BPA/AA/NPG                                                                            Type, Wt %                                                                           Wt % Solvent                                                                            Hours                                                                             Range, °C.                                                                   % Theor.                                                                           NVM Viscosity                      __________________________________________________________________________    2  2/2/1   0.1% H.sub.3 BO.sub.3                                                                7.5% Xylene                                                                             14.5                                                                              160-250                                                                             100  72  0.07                                             10% Aromatic 100                                            3  3/2/1   0.64% H.sub.3 BO.sub.3                                                               23% Aromatic 100                                                                        8   143-175                                                                             100  72  --                                        0.86% H.sub.3 PO.sub.3                                             4  2/2/1   0.3% H.sub.3 BO.sub.3                                                                20% Aromatic 100                                                                        8   140-200                                                                              84  --  --                                        1.0% H.sub.3 PO.sub.4                                              5  2/2/1   0.6% H.sub.3 BO.sub.3                                                                20% Aromatic 100                                                                        16  140-190                                                                              92  76  0.06                                      0.4% H.sub.3 PO.sub.4                                              __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________    Catalyst                    Reaction                                          EX.                                                                              Type       Wt. %                                                                             Solvent   Time, Hrs.                                                                          Temp. °C.                                                                    Conversion %                          __________________________________________________________________________    6  H.sub.3 BO.sub.3                                                                         0.15                                                                              10% Xylene                                                                              24    165-215                                                                             100                                      H.sub.3 PO.sub.3                                                                         0.20                                                                              20% Aromatic 100                                            7  Al(OOC--CH.sub.3).sub.2 OH                                                               0.65                                                                              12% Heptane                                                                             11    170-185                                                                             99                                       MSA*       0.30                                                            8  Al(OOC--CH.sub.3).sub.2 OH                                                               0.65                                                                              12% Heptane                                                                             9     165-190                                                                             99                                       MSA        0.10                                                            9  Mg(OOC--CH.sub.3).sub.2                                                                  0.40                                                                              12% Aromatic 100                                                                        24    190-230                                                                             81                                       MSA        0.10                                                            10 Zn(OOC--CH.sub.3).sub.2                                                                  0.5 12% Aromatic 100                                                                        9     175-190                                                                             100                                      MSA        0.1                                                             11 Zn(OOC--CH.sub.3).sub.2                                                                  0.5 25% Heptane                                                                             7     150-190                                                                             100                                      MSA        0.1                                                             12 Zn(OOC--CH.sub.3).sub.2                                                                  0.5 12% Aromatic 100                                                                        16    190-230                                                                             86                                    13 CaO        0.13                                                                              12% Aromatic 100                                                                        17    210-230                                                                             83                                    14 NaHCO.sub.3                                                                              0.2 12% Aromatic 100                                                                        18    200-230                                                                             88                                    15 H.sub.3 BO.sub.3                                                                         0.6 12% Aromatic 100                                                                        13.5  180-210                                                                             90                                       H.sub.3 PO.sub.3                                                                         0.2                                                             16 Zn(OOC--CH.sub.3).sub.2                                                                  0.5 12% Aromatic 100                                                                        13    190-210                                                                             86                                       H.sub.3 PO.sub.3                                                                         0.1                                                             17 Zn(OOC--CH.sub.3).sub.2                                                                  0.5 12% Aromatic 100                                                                        18.5  185-215                                                                             84                                       H.sub.3 PO.sub.3                                                                         0.3                                                             __________________________________________________________________________     *MSA  Methane Sulfonic Acid                                              

The container or can is then capped and sealed, placed on a roller andmixed until a homogeneous solution is obtained (about 30 minutes). Aftermixing, the container is allowed to stand about another 30 minutes toremove all air bubbles. The solution is then ready for application onmetal test panels via drawdown rods or spray equipment.

This particular solution has the following calculated characteristics:

nonvolatile content of 70 wt.%,

Cymel 303 (HMMM) at 25 wt.% of the binder solids (polyester+HMMM)

catalyst at 0.3 wt. % H₃ PO₃ based on binder solids (from resinsynthesis)

In this formulation, the curing catalyst is the residual synthesiscatalyst, and no additional curing catalyst is added. Strong acid numbermeasurements suggest the actual catalyst level may be about one-half ofthe original phosphorous acid charge value of Example 1.

Formulations similar to that of Example 18 may be made using otherdiphenol terminated resins such as prepared in Examples 2-17. Generallyspeaking, the amount of crosslinking agent incorporated into the resinmay range from about 15 to about 45% by weight, based on the combinedweight of the resin and added crosslinking agent. The inclusion of acrosslinking catalyst may not be required where the resin containssufficient residual esterification catalyst as in the case of Example18. In other cases it may be necessary to include additional catalystinto the resin formulation to effect a proper cure, such cases includingthose Where no catalyst is used in preparing the diester. Such catalystsmay be typically added as dilute solutions in alcohol.

For some of the more viscous resins, the procedure of Example 18 may bealtered slightly so that the diester resin and the solvent are added tothe jar first. This diluted resin solution is warmed in a steam bath andthen mixed on a roller until a homogeneous solution is obtained. Afterthis solution cools to room temperature, the remaining ingredients areadded and the complete formulation is again mixed on a roller to obtaina homogeneous solution.

The following example describes the preparation of cured films.

EXAMPLE 19

Thin films of the formulation of Example 18 are applied to steel testpanels via drawdowns and/or air spray. The basic procedures are outlinedin ASTM Test Procedure D823-87, Methods A and E. Test panels are eitheruntreated Type QD or Type S cold rolled steel panels obtained from theQ-Panel Company or polished Bonderite 1000 (iron-phosphate treatment)panels obtained from the Parker-Amchem Company. Panel sizes are either4"×8", 3"×6", 6"×12" or 3"×5".

A model 310277 Automatic Test Panel Spray Machine made by Spraymation,Inc. is used to spray panels (Method A above); wire-wound drawdown rodsand in some cases a Precision Laboratory Drawdown Machine (both from thePaul N. Gardner Company) are used to apply films via hand-pulleddrawdowns (Method E). Target dry film thicknesses are 1 mil.

After wet films are applied as described above, panels are allowed toflash-off solvents for about 10 minutes at room temperature. The filmsare then cured by baking them in a large oven. All panels lay in ahorizontal position during flash-off and baking. Backing schedules rangefrom 10 to 60 minutes at temperatures between 220° and 350° F.

The film property evaluations which are conducted with the cured panelsare as follows:

    ______________________________________                                        Property/Test   ASTM Reference                                                                             Comment                                          ______________________________________                                        Knoop Hardness  D1474        --                                               Pencil Hardness D3363        1                                                Direct Impact   D2794        2                                                Reverse Impact  D2794        2                                                Flexibility     D1737        3                                                Adhesion        D3359        --                                               Chemical Resistances                                                                          D1308        4                                                10% HCl                                                                       10% NaOH                                                                      Distilled H.sub.2 O                                                           Methyl Ethyl Ketone                                                           Xylene                                                                        Salt Spray (Fog)                                                                              B117         5                                                Humidity        D2247        6                                                Weathering      G53          7                                                Permeability    D1653        8                                                MEK Rubs        D3732        9                                                ______________________________________                                         Comments                                                                      1. Gouge hardness reported (not scratch hardness).                            2. 5/8 inch punch with 0.64 inch die; BONDERITE 1000 or QD panels. Values     are generally higher for QD panels.                                           3. Cylindrical mandrel.                                                       4. 24 hour spot tests; overall ratings: exc. > good > fair > poor; exc.       means no problems other than film softening during exposure and full          hardness recovery after 24 hr; poor indicates film lifted off surface or      blistered; good and fair indicate some softening after recovery and/or        visual gloss change (hazing); visual observations and pencil hardness         measurements made at 1 and 24 hours exposure and after 24 hr. recovery        with chemical removed.                                                        5. Panels have "X" scribe (about 1.5 in. long) near bottom of panels; 0 t     10 (best ratings according to ASTM standardized scoring system for            corrosion/rusting (ASTM D610) and blister size (ASTM D714); blister           frequency also according to ASTM D714; reported value is for corrosion        under film after 260 hr. exposure.                                            6. Similar scoring as for Salt Spray (comment 5 above); no scribes on         these panels; reported value is again for under film corrosion but after      570 hr. exposure.                                                             7. Accelerated weathering with Quv tester employing UVB313 bulbs from         QPanel Company; testing cycle 4 hr. UV at 60° C. alternating with      hr. moisture at 50°; reported value is 20 degree gloss loss (%)        after 500 hours total exposure; glosses measured in accordance with ASTM      D523; observations for checking (ASTM D660), cracking (ASTM D661),            chalking (ASTM D659), corrosion (ASTM D610) and blistering (ASTM D714)        also made.                                                                    8. Water vapor permeability via Method B, condition B of ASTM D1653;          values reported in g/m.sup.2 /24 hr.                                          9. MEK = methyl ethyl ketone; general solvent rub method value described      in paragraph 5.2 of ASTM D3732; maximum value tested is 250.             

The following examples demonstrate the preparation of bisphenolterminated diesters wherein no esterification catalyst is employed.

EXAMPLES 20-24

The process of Example 1 was repeated except that the boricacid/phosphorous acid catalyst system was omitted from the reactionmedium. Variations in solvents and polymerization conditions arereported in Table 3. Film properties are also reported in Table 3.

As is evident from the data in Table 3, in all cases the reaction takesplace without any added catalyst. Examples 23 and 24 are similar toexample 22 except the reaction time is extended to increase theconversion and lower the carboxylic acid number. A dramatic improvementin film properties results.

The following example demonstrates the use of various monomers toproduce bisphenol terminated diesters.

                                      TABLE 3                                     __________________________________________________________________________                        Reactions Conditions                                      Monomer                      Water                                                                              Product                                        Ratio,           Time                                                                              Temp Off-Take,                                                                          Acid #    Film Properties.sup.(a)           EX.                                                                              BPA/AA/NPG                                                                            Wt % Solvent                                                                           Hours                                                                             °C.                                                                         % Theor.                                                                           Carboxylic                                                                          NVM Hardness                                                                           Rev. I.                      __________________________________________________________________________    20 2/2/1   10% Xylene                                                                             12  180-250                                                                            92   24    94  13   225                          21 2/2/1   8% Aromatic 150                                                                        10  180-250                                                                            92   29    94  15   195                          22 2/2/1   8% Aromatic 150                                                                         7  180-250                                                                            87   43    93  16    33                          23 2/2/1   8% Aromatic 150                                                                        10  170-250                                                                            93   31    94  16   211                          24 2/2/1   8% Aromatic 150                                                                        13  180-250                                                                            96   22    91  16   205                          __________________________________________________________________________     .sup.(a) Films were prepared using 25.9% by weight Cymel 303 (based on        binder; e.g. Cymel plus resin); 0.15% PTSA; and a bake schedule of 30         minutes at 300° F.                                                

EXAMPLES 25-37

A number of bisphenol terminated diesters with different monomers wereproduced using a procedure similar to Example 1. The reaction conditionswere:

    ______________________________________                                        BPA:             1 mole                                                       Diacid:          0.5-1.5 mole                                                 Diol:            0-1 mole                                                     Catalyst:        1.5 g. Boric acid                                                             2.0 g. Phosphorous acid                                      Solvent:         100 g. xylene                                                                 100 g. Aromatic 100                                          Temp. Range:     150-200° C.                                           Time:            12-15 hours                                                  ______________________________________                                    

Clear films were made as in Examples 18 and 19 with 33% by weight Cymel303/resin, no catalyst, and a baking schedule of 30 min. at 300° F. Theresults are compiled in Table 4.

Included in these examples are bisphenol terminated dicarboxylic acidmaterials based on a dimer acid (Example 37) and n-decanoic acid(Example 35).

The following example shows the preparation of a bisphenol terminateddiester by a two-stage polycondensation technique. The advantage of thetwo-stage reaction is more complete incorporation of bisphenol into thepolymer. The much less reactive bisphenol is reacted with diacid in thefirst stage under very favorable reaction conditions which include anexcess of diacid and no diol present. Then the first stage product issubsequently reacted with diol in the second stage.

                                      TABLE 4                                     __________________________________________________________________________                            Gardner                                                                            Strong                                                                            Carbox.  Clear Film Prop                     EX.                                                                              Type.sup.(a)                                                                           Ratio                                                                             % Conversion                                                                          Color                                                                              Acid #                                                                            Acid #                                                                             NVM Hard                                                                              R.I.                            __________________________________________________________________________    25 BPA/AA/NPG                                                                             2/2/1                                                                             94      11   .9  15.1 89   8   66                             26 BPA/AA/NPG                                                                             2/3/2                                                                             96      5    .9  13.3 88   7  >260                            27 BPA/SA/NPG                                                                             2/2/1                                                                             92      8    .7  23.5 88  24   8                              28 BPA/SA/NPG                                                                             2/3/2                                                                             96      3    1.0 15.2 91  20  --                              29 BPA/SA/n-C.sub.10                                                                      2/2/1                                                                             95      12   .9  12.1 75  11   60                             30 BPA/SA/CHDM                                                                            2/2/1                                                                             93      13   1.0 16.4 78  21   4                              31 BPA/AA/EG                                                                              2/2/1                                                                             83      16   .8  46.2 85  20   32                             32 BPA/AA/EG                                                                              2/3/2                                                                             89      14   .8  36.6 90  11  244                             33 BPA/AA/n-C.sub.6                                                                       2/2/1                                                                             94      16   .7  16.6 90  15  180                             34 BPA/C.sub.10 /NPG                                                                      2/2/1                                                                             98      5    1.8 5.0  89   2  >260                            35 BPA/C.sub.10 /--                                                                       2/1/0                                                                             98      16   1.3 3.8  83  17  200                             36 BPA/DA/NPG                                                                             2/2/1                                                                             95      1    .9  5.6  90  --  --                              37 BPA/DA/--                                                                              2/1/0                                                                             91      13   .7  8.6  80   1  165                             __________________________________________________________________________     .sup.(a)                                                                      SA = succinc acid                                                             nC.sub.10 = 1,10  decanediol                                                  CHDM = Cyclohexanedimethanol                                                  EG = Ethylene Glycol                                                          nC.sub.6 = 1,6  hexanediol                                                    C.sub.10 = ndecandioioic acid                                                 DA = Dimer acid; a C.sub.36 dibasic acid produced by dimerization of a        mixture of natural occurring unsaturated fatty acids, such as linoleic        acid.   EXAMPLE                                                          

38

Into a 2 liter four-necked flask equipped with a mechanical stirrer,heating mantle, nitrogen sparget, 10 inch column packed with glass beadson top of which is a Dean Stark trap and chilled water condenser, andthermometer fitted with temperature controller, are charged 456.6 g.Bisphenol A, 292 g. Adipic Acid, 3.75 g. Zinc acetate, 0.76 g. Methanesulfonic acid and 200 g. Aromatic 100. The contents are heated tomelting, stirred, and heating is continued to about 170° C. where thesolvent/water azeotrope starts to distill out. The solvent iscontinuously removed from the Dean Stark trap and returned to the flask.Water removal is used to monitor the reaction. Heating is continued andthe temperature allowed to rise as the water is removed to a finaltemperature of 180° C. The reaction is stopped after their theoreticalamount of water has been removed, which takes about 4 hours. The productis then cooled to 100° C. and 104.0 g. NPG is charged to the reactionmixture. The mixture is heated at 170°-190° C. for an additional 9hours. The water is removed as before and the total conversion is 93%.The product has an NVM =73.1% and a reduced viscosity of 0.057 for a 10%solution in glacial acetic acid. Clear films are made and evaluated asin Examples 18 and 19.

EXAMPLES 39-48

Other similar bisphenol terminated diesters are prepared as in Example38 by simply substituting different monomers, monomer rates, solvents,catalysts, and temperature/time schedules. The results are shown inTable 5.

The following examples demonstrate the relationship of resin color onthe type of catalyst employed in synthesis.

EXAMPLES 49-56

The process of Example 1 was repeated using a reaction mixture of 1.0moles BPA, 1.0 moles AA, 0.5 moles NPG, 50 g. xylene, and 100 g.Aromatic 100 to study the effect of catalyst and reaction conditions onthe color of the resin product. Gardner colors of the resin product wereobtained with Gardner color standards. Clear films were prepared as inExamples 18 and 19, with a Cymel 303/resin at 33% by weight, no addedcure catalyst, and a bake schedule of 10 minutes at 260° F. The resultsare shown in Table 6.

The following examples demonstrate that excellent combinations of filmproperties can be obtained for a variety of compositions and bakingconditions.

EXAMPLES 57-63

                                      TABLE 5                                     __________________________________________________________________________                                                             Reaction                                        Stage 1      Stage 2.sup.(a)  Product              Monomer                            Water        Water    Film                 Ratio      Catalyst        Time                                                                             Temp Off-Take                                                                           Time                                                                             Temp Off-Take                                                                           Carbox                                                                            Props..sup.(b)       EX.                                                                              BPA/AA/NPG                                                                            Type/WT %                                                                           Solvent   Hrs.                                                                             °C.                                                                         % Theor.                                                                           Hrs.                                                                             °C.                                                                         % Theor.                                                                           Acid                                                                              Hard                                                                             R.I.              __________________________________________________________________________    39 2/2/1   H.sub.3 BO.sub.3 /0.6                                                               20% Aromatic 100                                                                        7  170-220                                                                            47.2 6.5                                                                              183-220                                                                            100  16.9                                                                              12.0                                                                              20                          H.sub.3 PO.sub.3 /0.4                                              40 2/2/1   None  20% Aromatic 100                                                                        5  210-230                                                                            50   8  170-210                                                                            91.0 39.3                                                                              13.8                                                                              63               41 2/2/1.25                                                                              None  10% Aromatic 100                                                                        3.5                                                                              210-230                                                                            48.5 3  210-230                                                                            99.2 25.1                                                                              13.0                                                                             103               42 2/2/1.5 None  10% Aromatic 100                                                                        3  210-220                                                                            33   9  210-220                                                                            100  18.0                                                                              8.2                                                                              244               43 2/2/1   None  10% Aromatic 100                                                                        7  200-234                                                                            59   5  200-232                                                                            92   27.4                                                                              14.7                                                                             161               44 2/2/1   None  10% Aromatic 100                                                                        8  200-230                                                                            57.5 4.5                                                                              185-230                                                                            94.2 29.0                                                                              13.7                                                                             195               45 2/2/1   None  7.3% Toluene                                                                            2  225-240                                                                            60   6  180-240                                                                            94   14.9                                                                              12.5                                                                             198               46 2/2/1   None  5.5% Xylene                                                                             7  210-250                                                                            53.2 11 200-250                                                                            89.2 19.5                                                                              12.2                                                                             218               47 2/2/1   None  10.5% Aromatic 100                                                                      7  210-240                                                                            60.5 5  190-230                                                                            99.6 29.1                                                                              15.0                                                                             178               48 2/2/1.sup.(c)                                                                         None  12% Aromatic 100                                                                        4  190-230                                                                            50   14 190-230                                                                            94   --  19.0                                                                              0                __________________________________________________________________________     .sup.(a) Two stage esterification involved initial reaction of BPA with       AA, followed by second stage reaction of this product with NPG.               .sup.(b) Films were prepared using 25.9% Cymel 303 (based on binder; e.g.     Cymel plus resin); 0.15% para Toluene Sulfonic Acid (pTSA) and a bal. at      300° F.                                                                .sup.(c) Phenolphthalein substituted for bisphenol A. Hardness was            increased at expense of flexibility.                                     

                                      TABLE 6                                     __________________________________________________________________________                                           Clear Film                             Catalyst     Temperature                                                                          Reaction      Gardner                                                                            Properties                             EX.                                                                              System    Range, °C.                                                                    Time, hrs.                                                                          % Conversion                                                                          Color                                                                              Hard                                                                             R.I.                                                                             Comments                         __________________________________________________________________________    49 2.0 g. H.sub.3 PO.sub.3                                                                 150-204                                                                              10    94      14    4  <10                                                                             (1)                                 1.5 g. H.sub.3 BO.sub.3                                                    50 1.6 g. H.sub.2 SO.sub.4                                                                 133-146                                                                              15    100     18   -- -- (1)                                 6.1 g. H.sub.3 BO.sub.3                                                    51 4.6 g. H.sub.3 PO.sub.4 (85%)                                                           156-175                                                                              37    92      12   -- -- (1)                              52 4.6 g. H.sub.3 PO.sub.4 (85%)                                                           159-172                                                                              29    86      11   -- -- (1)                                 4.0 g. Ph.sub.3 P                                                          53 4.0 g. (PhO).sub.3 P                                                                    160-187                                                                              34    91       8   -- -- (1)                              54 4.0 g. H.sub.3 PO.sub.3                                                                 151-173                                                                              14    94       3   17  140                                                                             (2)                              55 4.0 g. H.sub.3 PO.sub.3                                                                 155-170                                                                              13    96       2   18   180                                                                            (2)                                 4.0 g. (PhO).sub.3 P                                                       56 8.1 g. H.sub.3 PO.sub.2 (50%)                                                           142-170                                                                              16    95      <1   21 >200                                                                             (2), (3)                         __________________________________________________________________________     Comments:                                                                     (1) These catalyst systems gave dark colored resin solutions despite          conversion levels and reaction conditions.                                    (2) Catalysts which are reducing agents and low reaction temperatures gav     improved color and good film properties.                                      (3) Hypophosphorous acid catalyst gave best color.                       

A large batch of resin was produced in a manner similar to that inExample 21. Clear formulations of this large batch were then preparedwith a melamine formaldehyde crosslinking agent (HMMM as CYMEL 303), ablocked PTSA catalyst (Byk Chemie VP 451) and suitable solvents.Formulation compositions contained HMMM at concentrations between 30 and40 wt% of binder solids and PTSA at concentrations between 0.1 and 1.5wt% based on binder solids. The formulations were drawn down toapproximately 1 rail dry films on cold rolled steel test panels (Q-PanelCompany, type QD ) and baked at temperatures between 220° and 300° F.for times between 10 and 50 minutes.

Cured films were evaluated for Knoop hardness, reverse impact, MEKdouble rubs, gloss retention after 1 hour immersion in boiling water,and resistance to 10% NaOH (24 hour spot test). Results indicate thatexcellent combinations of film properties can be obtained for a varietyof compositions and baking conditions as shown in Table 7.

The following example describes the preparation of pigmented paints.

EXAMPLE 64

Pigmented paints are prepared by grinding titanium dioxide (TiO₂) intothe clear formulations using a high speed disk disperser such as theByk-Chemie DISPERMAT Model CV. First a mill base containing TiO₂,bisphenol terminated diester resin, and solvent is ground; then thismill base is let down with the remaining ingredients in the formulation.Specific weights for one paint are given below:

Mill Base:

300 g. of bisphenol terminated diester resin (similar to that resindescribed in Example 1 but NVM =S6.5%)

                                      TABLE 7                                     __________________________________________________________________________                Bake                                                                              Bake    Clear Film Tests                                         HMMM Cat Temp,                                                                             Time,                                                                             Knoop                                                                             Reverse                                                                            MEK Gloss                                                                             NaOH                                     EX.                                                                              WT % WT. %                                                                             °F.                                                                        Min.                                                                              Hard                                                                              Impact                                                                             Rubs                                                                              Retent.                                                                           Spot                                     __________________________________________________________________________    57 30   0.3 300 10  15.5                                                                               83  >200                                                                              21.8                                                                              no effect                                58 30   0.3 300 10  17.0                                                                               85  >200                                                                              13.6                                                                              no effect                                59 30   0.1 300 30  14.6                                                                              112  >200                                                                              54.3                                                                              no effect                                60 40   0.3 260 50  14.5                                                                              106  >200                                                                              22.9                                                                              no effect                                61 40   1.0 220 30  16.3                                                                              150  >200                                                                              18.5                                                                              no effect                                62 30   0.5 260 10  15.5                                                                              125  >200                                                                              10.7                                                                              no effect                                63 30   0.5 260 10  14.2                                                                              120  >200                                                                              3.5 discolored                               __________________________________________________________________________

300 g. TiO₂ (DuPont TI-PURE R-960)

20 g. Xylene

Complete Formulation:

200 g. Mill Base

9.6 g. bisphenol terminated diester resin (nonvolatile content 86.5%)

31.1 g. CAnnel 303 (HMMM)

2.0 g. Byk-Chemie Product VP-451 (amine blocked p-TSA)

21.7 g. EXXATE 700 Solvent (a mixture of heptyl acetates sold by ExxonChemical Company)

29.7 g. Xylene

This paint has a nonvolatile content of 75.5 wt.%, a pigment/binderweight ratio of 0.8, a HMMM concentration of 24 wt.% of binder and acatalyst level of 0.27 wt. % p-TSA based on binder.

The paint may then be applied to an appropriate substrate by drawdown orspraying, followed by baking as set forth above.

Other paints may be made with different resins; HMMM concentrationsbetween 20 and 35 wt% of binder; amine-blocked P-TSA, phosphoric acidcatalysts; catalyst levels between 0 and 0.6 wt.% on binder;pigment/binder weight ratios between 0.8 and 1.1 and variety of solventsincluding mixtures of Aromatic 100, Aromatic 150, Xylene, n-BuOh, EXXATE600 solvent, EXXATE 700 solvent, methyl amyl ketone and methyl ethylketone.

Commercial pigment wetting/dispersing additives may also be used in somepaints. These include Byk-Chemie ANTI-TERRA U, DuPont ELVACITE AB 1015and ICI SOLSPERSE 24000. They are used at concentrations between 1 and2.5 wt.% active ingredient based on pigment. Dow Corning 57 flowadditive may also be added to some formulations, typically at aconcentration of 0.1 wt.% of the formulation.

What is claimed is:
 1. A process for preparing a non-liquid crystalline,phenol terminated diester composition comprising:i) forming a mixturecomprising:a. an aromatic dihydroxy compound having the formula HO-A-OH,wherein A is a divalent aromatic radical selected from the groupconsisting of phenylene, naphthylene and bis-phenylene radicals, b. adicarboxylic acid having the formula ##STR16## wherein R is a divalentaliphatic radical or a mixture of such radicals having from 2 to 40carbon atoms; and c. a diol having the formula HO--R₁ --OH wherein R₁ isa divalent aliphatic or cycloaliphatic radical or mixtures thereofhaving from 2 to 40 carbon atoms, said component (b) being present inmolar excess with respect to component (c), ii) heating said mixture ina first stage at a temperature of from about 140° C. to about 220° C. toform a carboxy terminated polyester, and iii) further heating theproduct of step (ii) above the temperature of step (ii) to a temperatureof up to about 260° C. to form the phenol terminated diester.
 2. Theprocess of claim 1 wherein said mixture further comprises:d. adicarboxylic acid having the formula ##STR17## wherein R₂ is a divalentaromatic or aliphatic radical or mixtures thereof having from 2 to 40carbon atoms.
 3. The process of claim 1 wherein the molar ratio ofcomponent (a) to (b) to (c) is about 2 : n+1) : n wherein n representsthe number of moles of component (c).
 4. The process of claim 1 whereinsaid mixture further includes catalytic quantities of an acidicesterification catalyst.
 5. The process of claim 4 wherein said catalystcomprises a mixture of a Group I to Group VI metal oxide, hydroxide orweak acid salt thereof, with a strong acid.
 6. The process of claim 5wherein said strong acid comprises methane sulfonic acid.
 7. The processof claim 5 wherein said metal salt is selected from the group consistingof magnesium acetate, aluminum hydroxy acetate and zinc acetate.
 8. Theprocess of claim 5 wherein said first stage reaction is conducted at atemperature of from about 140° C. up to about 200° C.
 9. The process ofclaim 4 wherein said catalyst comprises a phosphorus-containing acid ora mixture thereof with a co-catalyst selected from the group consistingof boric acid, boron oxide and a Group I to Group VI metal oxide,hydroxide or weak acid salt thereof.
 10. The process of claim 9 whereinsaid catalyst comprises a mixture of boric acid and hypophosphorousacid.
 11. The process of claim 9 wherein said catalyst ishypophosphorous acid.
 12. The process of claim 9 wherein said firststage reaction is conducted at a temperature of from about 150° C. toabout 200° C.
 13. The process of claim 12 wherein said temperature isfrom about 140° C. to about 180° C.
 14. The process of claim 4 whereinsaid catalyst is present at a level of from about 0.01 up to about 2.0weight percent, based on the weight of reactants.
 15. The process ofclaim 1 wherein A is a bis-phenylene radical having the structure:##STR18## wherein m is 0 or 1, X is selected from the group consistingof a C₁ to C₁₂ hydrocarbon divalent radical a cycloaliphatic divalentradical having 5 to 12 carbon atoms, S, O, and ##STR19## wherein R₄ maybe the same or different and is selected from the group consisting ofhydrogen, C₁ to C₆ alkyl, cycloalkyl, phenyl and CF₃, and Y and Z areindependently selected from the group consisting of hydrogen, halogen,C₁ to C₄ alkyl and C₁ to C₄ alkoxy.
 16. The process of claim 15 whereinX is ##STR20##
 17. The process of claim 1 wherein said reaction isconducted in organic solvent.
 18. A process for preparing a non-liquidcrystalline phenol terminated diester composition comprising:1. forminga mixture of:a. an aromatic dihydroxy compound having the formulaHO--A--OH, wherein A is a divalent aromatic radical selected from thegroup consisting of phenylene, naphthylene and bis-phenylene radicals,and b. an aliphatic dicarboxylic acid having the formula ##STR21##wherein R is a divalent aliphatic radical or a mixture of such radicalshaving from about 8 to 40 carbon atoms, said component (a) being presentin a molar ratio of at least about 2:1 with respect to component (b),and
 2. heating said mixture at a temperature of from about 140° C. tobelow about 250° C. to form a phenol terminated diester.
 19. The processof claim 18 wherein said aliphatic dicarboxylic acid is a C₃₆ dimeracid.
 20. The process of claim 18 wherein said mixture further includescatalytic quantities of an acidic esterification catalyst.
 21. Theprocess of claim 20 wherein said catalyst comprises hypophosphorousacid.
 22. The process of claim 18 wherein said reaction is conducted inorganic solvent.
 23. A process for preparing a non-liquid crystalline,phenol terminated diester composition comprising:
 1. forming a mixtureof:a. an aromatic dihydroxy compound having the formula HO-A-OH whereinA is a divalent aromatic radical selected from the group consisting ofphenylene, naphthylene and bis-phenylene radicals, and b. a dicarboxylicacid having the formula ##STR22## wherein R is a divalent aliphaticradical or mixture of such radicals having from 2 to 40 carbon atoms, 2.heating said mixture at a temperature of from about 140° C. to about200° C. for a period of time sufficient to form the partial ester ofsaid dicarboxylic acid,3. adding to said reaction mixture from step 2 adiol having the formula HO--R₁ --OH wherein R₁ is a divalent aliphaticor cycloaliphatic radical or a mixture of such radicals having from 2 to40 carbon atoms, while maintaining said reaction temperature below about200° C., and
 4. recovering said phenol terminated diester composition.24. The process of claim 23 wherein the mole ratio of component (b) tocomponent (a) ranges from about 10:1 to about 1:1.
 25. The process ofclaim 23 wherein said diol added in step 3 is mixed with a dicarboxylicacid having the formula ##STR23## wherein R₂ is a divalent aromatic oraliphatic radical or mixtures thereof having from 2 to 40 carbon atoms.26. The process of claim 23 wherein said reaction mixture from step 3 isheated to a temperature up to 230° C. prior to recovery of said phenolterminated diester.
 27. The process of claim 23 wherein said reactionmixture further includes catalytic quantities of an acidicesterification catalyst.
 28. The process of claim 27 wherein saidcatalyst comprises hypophosphorous acid.
 29. The process of claim 23wherein said reaction is conducted in organic solvent.